1. Field of the Invention
The present invention relates to a semiconductor device having a novel structure. More particularly, the invention relates to a semiconductor device effective for protecting from external surge voltages an element connected to an input or output terminal of a semiconductor device of the insulated gate type (hereinafter referred to as "IG type").
2. Description of the Prior Art
In the conventional IC of the complementary MOS type (hereinafter referred to as "CMOS"), an element connected to an input or output terminal of the CMOSIC may be protected from external surge voltages by an input gate-protecting diffusion resistance layer formed in a semiconductor substrate on which the CMOSIC is formed and by a device for protecting the gate by a p-n diode. In some cases, however, in this protecting device, when a thyristor constructed of a parasitic transistor is turned on, a large current flows and chips are burnt out. Accordingly, it is construed that this protecting device cannot be a complete protecting device.